The invention concerns a double-sided wall or folding door of panel elements which are hinged in pairs along their inner edges to one another and/or to vertical mounting strips. These panel elements are suspended in a ceiling runner and are horizontally movable, with the elements belonging to one wall side lying in a single plane when the folding wall is in a closed condition.
In usual current folding walls, the hinge-squares formed by opposing element pairs remain rhombic-shaped in cross section and the folding wall sides are therefore uneven even in the wall closed condition. Folding walls of the type considered here have the advantage that in the closed position they provide a flush wall appearance or character interrupted only by vertical grooves in the area of the necessarily resilient mounting strips. "Pulling flush" such folding walls does, however, involve difficulties both in closing and opening movement. As long as all the hinge axes of closed folding wall side elements lie in one plane (desirable for both constructional and esthetic reasons), there is no momentum available for swinging the elements open, when wall folding or opening is desired, because the opening force runs in the planes of the elements themselves. The same holds true for wall closing, where the force necessary for putting the elements into the side planes is lacking, because they are vertical to the closing tension exerted in those side planes.
Up until now, therefore, special measures have had to be taken to overcome these difficulties, and these measures have been taken at the expense of production cost, operational simplicity and safety, as well as the external appearance of the folding wall.
The basic object of the invention is to create a "flush-extending" folding wall which affords a maximum of operational safety with simple construction and attractive appearance.
The present invention accomplishes this object by mounting horizontal brackets on at least one element of each wall panel element pair, and between two mounting strips, or on the elements opposite each other. These horizontal brackets have inwardly offset bracket arms, which in each case lie approximately on the hinge axis between the element and the mounting strip. The bracket arms extend at an obtuse angle opposite the element in the closed position of the folding wall into the area of the mounting strip. By having a spring set between the free ends of the two opposing brackets, torsional forces are exerted around the hinge axes on the wall elements. These forces act in a closed folding wall in the closing direction; in an open folding wall, the forces act in the opening direction. When the free ends of the bracket arms to which the spring is attached are in the closed position, the arm ends are on one side of a plane that runs through the two opposing hinge axes vertical to the wall plane. When the free ends of the bracket arms are in the open position, they are located on the other side of this plane. In other words, the arms are oriented in such a way that the free arms ends lie outside of the cross section quadrangle bounded by the involved elements when the folding wall is in its closed position. In this way, of course, the spring produces torsional force in different directions around the hinge axes in the wall closed position and in the wall open position, despite the constant effective direction of the force of the spring.
If the folding wall is open, the individual panel elements lie in planes vertical to the wall plane, and the two brackets associated with the wall element pair (which in the closed condition of the folding wall face each other), now lie generally in one of these vertical planes. The brackets extend diagonally with bracket arms -- homologously opposed -- out of that wall element plane, and the spring acting between the free ends of the bracket arms exerts a torsional force around the hinge axes around which the two elements are hinged to pivot on the respective mounting strip so as to maintain this vertical attitude. The elements cannot swing past the vertical plane position, because their front edges facing the mounting strip come to rest on the strip outer side surface.
When the folding wall begins to close, the spring forces, which keep the elements tensioned in their transverse position as described above, are immediately overcome, although as the elements begin their turns out of the transverse position into the wall or panel planes, the spring forces at first even increase. This is due to the fact that the brackets swing with the wall elements, and their free ends pass through an unstable dead-center position in the course of this swinging movement in which the spring force is greatest but acts neither in the closing direction or in the opening direction.
This dead-center position occurs when the bracket arms are at less than 135.degree. to the elements, and when the elements have reached a 45.degree. position with reference to the panel plane, that is, when the folding wall is half closed. In this position the bracket arms are about in the above-described plane passing through the two opposing hinge axes. If the folding wall is pulled farther into its closed position, each spring exerts a torsional force on the brackets, and thus on the elements, which is exerted in the open position and forces the elements into the closed position in which they find themselves within the given plane of the panels.
There is of course no difficulty in swinging the elements of the wall beyond the dead-center point into the open position with a mere push against the closing force of the spring, as long as the elements are not yet completely in the closed position. But for the reasons given above, the opening of the folding wall or of its individual sections formed of any two facing element-pairs is theoretically impossible as soon as the elements are swung completely into their panel plane. However, it was found that this theoretical impossibility actually does not occur in practice, because of inevitable wall component and installation irregularities. Just a slight displacement of the individual hinge axes with respect to the common panel plane suffices to make possible the opening of the individual folding wall sections against the closing forces exerted by the springs in this position.
In order to simplify and facilitate opening the closed folding wall, a refinement of the invention provides pushers. These pushers exert a pressure on the bracket arms within the wall plane, and the arms correspondingly exert torsional forces directed against the spring force. In this way the brackets receive an "initial impulse" which swings each associated element out of its closed position. As previously stated, even a relatively slight oblique posture of the elements vis-a-vis their panel planes suffices to bring about further wall opening action without any trouble.
The pushers can act particularly and directly on the springs, and a wall can be equipped with an actuating device on the front end for its opening. A pusher can be operationally connected with the actuating device to energize the spring situated in the area of the foremost mounting strip, while the activation of the rest of the pushers takes place in each case through the advance of the mounting strips in the opening direction as the wall moves. In this way, when the wall is opened first its foremost section consisting of two opposing element pair is completely opened, then the next one, then the third, etc., while any not yet opened sections remain in their closed position. With the traditional folding doors equipped with so-called "Nuremberg Shears," on the other hand, all folding wall sections are moved simultaneously.